Climate Change and Mitigation REU - Summer 2014

Soil Carbon Sequestration

 

• What is it?

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Terrestrial carbon sequestration consists of the capturing and storing of atmospheric carbon dioxide (CO2) by plants and the storage of carbon in soil. This mechanism gives great potential to mitigating greenhouse gases but it is important to know that soil can act both as a carbon sink and a carbon source. In order for soil to be used as a carbon sink, we must take in account all the things that affect soil carbon: e.g. climate, parent geological materials, managment practices, and the type of vegetation. 

 

Changing agricultural land management allows us to manipulate carbon sequestration. By studying the mechanisms behind soil carbon sequestration, researchers have found better managment practices which are implemented in some areas around the world. Some of these better managment practices involve reduced conventional tillage and no-till systems. This latter one is the most preferred method as it allows for the soil to remain intact, which also allows for more aggregate stability. 

 

• Why is it important?

 

Atmospheric carbon dioxide (CO2) levels are rising as fossil fuel consumption increases, while natural sinks, such as forests, wetlands, and healthy soil, are slowly being destroyed. This gives rise to climate change, which may impact us all in some way or form, severe or not. Understanding soil carbon sequestration, a short term strategy to mitigate climate change while more permanent solutions are being researched (Lal, 2004), will serve essential to increase the carbon (C) storage in soils. As C cycles, it diffuses into the ocean or gets taken up by plants through photosynthesis in the form of CO2. When plant tissue decomposes, microorganisms convert some of this C into soil organic carbon (SOC). This form of C is easily oxidized and can therefore quickly be released back into the atmosphere.  Longer term storage of C can be achieved through chemical stabilization (through mineral adsorption), chemical recalcitrance (through alteration of organic carbon form), and physical protection (e.g. burial within aggregates). Soil organic matter (SOM) protected by these mechanisms will eventually be subjected to decomposition through a variety of ways. It is therefore important to continuously add organic materials to the soil, especially through plant residues (Baldock, 2000), and to keep the soil as intact as possible through no-till or reduced till management.

 

• About this study:

 

This study looks at how minerals affect the mechanisms behind SOC stabilization in temperate agroecosystems, which will create insight on how to optimize C sequestration. For this study, soil samples were collected from plots at the North Agronomy Farm in Manhattan, KS. 

 

Objectives

 

• Determine the impact of different managment practices on amorphous (reactive) Mn, Fe, and Al in different soil aggregate fractions.​

• Evaluate the effect of amorphous Mn, Fe and Al on SOC sequestration by establishing correlations between different fractions of SOC and amorphous mineral concentrations.